package org.apache.commons.net.ssh.util;


/**
 * <p>
 * Encodes and decodes to and from Base64 notation.
 * </p>
 * <p>
 * Homepage: <a href="http://iharder.net/base64">http://iharder.net/base64</a>.
 * </p>
 * 
 * <p>
 * Example:
 * </p>
 * 
 * <code>String encoded = Base64.encode( myByteArray );</code> <br />
 * <code>byte[] myByteArray = Base64.decode( encoded );</code>
 * 
 * <p>
 * The <tt>options</tt> parameter, which appears in a few places, is used to pass several pieces of
 * information to the encoder. In the "higher level" methods such as encodeBytes( bytes, options )
 * the options parameter can be used to indicate such things as first gzipping the bytes before
 * encoding them, not inserting linefeeds, and encoding using the URL-safe and Ordered dialects.
 * </p>
 * 
 * <p>
 * Note, according to <a href="http://www.faqs.org/rfcs/rfc3548.html">RFC3548</a>, Section 2.1,
 * implementations should not add line feeds unless explicitly told to do so. I've got Base64 set to
 * this behavior now, although earlier versions broke lines by default.
 * </p>
 * 
 * <p>
 * The constants defined in Base64 can be OR-ed together to combine options, so you might make a
 * call like this:
 * </p>
 * 
 * <code>String encoded = Base64.encodeBytes( mybytes, Base64.GZIP | Base64.DO_BREAK_LINES );</code>
 * <p>
 * to compress the data before encoding it and then making the output have newline characters.
 * </p>
 * <p>
 * Also...
 * </p>
 * <code>String encoded = Base64.encodeBytes( crazyString.getBytes() );</code>
 * 
 * <p>
 * I am placing this code in the Public Domain. Do with it as you will. This software comes with no
 * guarantees or warranties but with plenty of well-wishing instead! Please visit <a
 * href="http://iharder.net/base64">http://iharder.net/base64</a> periodically to check for updates
 * or to contribute improvements.
 * </p>
 * 
 * @author Robert Harder
 * @author rob@iharder.net
 * @version 2.3.3
 */
public class Base64
{
    
    /**
     * A {@link Base64.InputStream} will read data from another <tt>java.io.InputStream</tt>, given
     * in the constructor, and encode/decode to/from Base64 notation on the fly.
     * 
     * @see Base64
     * @since 1.3
     */
    public static class InputStream extends java.io.FilterInputStream
    {
        
        private final boolean encode; // Encoding or decoding
        private int position; // Current position in the buffer
        private final byte[] buffer; // Small buffer holding converted data
        private final int bufferLength; // Length of buffer (3 or 4)
        private int numSigBytes; // Number of meaningful bytes in the buffer
        private int lineLength;
        private final boolean breakLines; // Break lines at less than 80 characters
        private final int options; // Record options used to create the stream.
        // private final byte[] alphabet; // Local copies to avoid extra method calls
        private final byte[] decodabet; // Local copies to avoid extra method calls
        
        /**
         * Constructs a {@link Base64.InputStream} in DECODE mode.
         * 
         * @param in
         *            the <tt>java.io.InputStream</tt> from which to read data.
         * @since 1.3
         */
        public InputStream(java.io.InputStream in)
        {
            this(in, DECODE);
        } // end constructor
        
        /**
         * Constructs a {@link Base64.InputStream} in either ENCODE or DECODE mode.
         * <p>
         * Valid options:
         * 
         * <pre>
         *   ENCODE or DECODE: Encode or Decode as data is read.
         *   DO_BREAK_LINES: break lines at 76 characters
         *     (only meaningful when encoding)&lt;/i&gt;
         * </pre>
         * <p>
         * Example: <code>new Base64.InputStream( in, Base64.DECODE )</code>
         * 
         * 
         * @param in
         *            the <tt>java.io.InputStream</tt> from which to read data.
         * @param options
         *            Specified options
         * @see Base64#ENCODE
         * @see Base64#DECODE
         * @see Base64#DO_BREAK_LINES
         * @since 2.0
         */
        public InputStream(java.io.InputStream in, int options)
        {
            
            super(in);
            this.options = options; // Record for later
            breakLines = (options & DO_BREAK_LINES) > 0;
            encode = (options & ENCODE) > 0;
            bufferLength = encode ? 4 : 3;
            buffer = new byte[bufferLength];
            position = -1;
            lineLength = 0;
            // alphabet = getAlphabet(options);
            decodabet = getDecodabet(options);
        } // end constructor
        
        /**
         * Reads enough of the input stream to convert to/from Base64 and returns the next byte.
         * 
         * @return next byte
         * @since 1.3
         */
        @Override
        public int read() throws java.io.IOException
        {
            
            // Do we need to get data?
            if (position < 0)
                if (encode)
                {
                    byte[] b3 = new byte[3];
                    int numBinaryBytes = 0;
                    for (int i = 0; i < 3; i++)
                    {
                        int b = in.read();
                        
                        // If end of stream, b is -1.
                        if (b >= 0)
                        {
                            b3[i] = (byte) b;
                            numBinaryBytes++;
                        } else
                            break; // out of for loop
                            
                    } // end for: each needed input byte
                    
                    if (numBinaryBytes > 0)
                    {
                        encode3to4(b3, 0, numBinaryBytes, buffer, 0, options);
                        position = 0;
                        numSigBytes = 4;
                    } // end if: got data
                    else
                        return -1; // Must be end of stream
                } // end if: encoding
                
                // Else decoding
                else
                {
                    byte[] b4 = new byte[4];
                    int i = 0;
                    for (i = 0; i < 4; i++)
                    {
                        // Read four "meaningful" bytes:
                        int b = 0;
                        do
                            b = in.read();
                        while (b >= 0 && decodabet[b & 0x7f] <= WHITE_SPACE_ENC);
                        
                        if (b < 0)
                            break; // Reads a -1 if end of stream
                            
                        b4[i] = (byte) b;
                    } // end for: each needed input byte
                    
                    if (i == 4)
                    {
                        numSigBytes = decode4to3(b4, 0, buffer, 0, options);
                        position = 0;
                    } // end if: got four characters
                    else if (i == 0)
                        return -1;
                    else
                        // Must have broken out from above.
                        throw new java.io.IOException("Improperly padded Base64 input.");
                    
                } // end else: decode
                
            // Got data?
            if (position >= 0)
            {
                // End of relevant data?
                if ( /* !encode && */position >= numSigBytes)
                    return -1;
                
                if (encode && breakLines && lineLength >= MAX_LINE_LENGTH)
                {
                    lineLength = 0;
                    return '\n';
                } // end if
                else
                {
                    lineLength++; // This isn't important when decoding
                    // but throwing an extra "if" seems
                    // just as wasteful.
                    
                    int b = buffer[position++];
                    
                    if (position >= bufferLength)
                        position = -1;
                    
                    return b & 0xFF; // This is how you "cast" a byte that's
                    // intended to be unsigned.
                } // end else
            } // end if: position >= 0
            else
                throw new java.io.IOException("Error in Base64 code reading stream.");
        } // end read
        
        /**
         * Calls {@link #read()} repeatedly until the end of stream is reached or <var>len</var>
         * bytes are read. Returns number of bytes read into array or -1 if end of stream is
         * encountered.
         * 
         * @param dest
         *            array to hold values
         * @param off
         *            offset for array
         * @param len
         *            max number of bytes to read into array
         * @return bytes read into array or -1 if end of stream is encountered.
         * @since 1.3
         */
        @Override
        public int read(byte[] dest, int off, int len) throws java.io.IOException
        {
            int i;
            int b;
            for (i = 0; i < len; i++)
            {
                b = read();
                
                if (b >= 0)
                    dest[off + i] = (byte) b;
                else if (i == 0)
                    return -1;
                else
                    break; // Out of 'for' loop
            } // end for: each byte read
            return i;
        } // end read
        
    } // end inner class InputStream
    
    /**
     * A {@link Base64.OutputStream} will write data to another <tt>java.io.OutputStream</tt>, given
     * in the constructor, and encode/decode to/from Base64 notation on the fly.
     * 
     * @see Base64
     * @since 1.3
     */
    public static class OutputStream extends java.io.FilterOutputStream
    {
        
        private final boolean encode;
        private int position;
        private byte[] buffer;
        private final int bufferLength;
        private int lineLength;
        private final boolean breakLines;
        private final byte[] b4; // Scratch used in a few places
        private boolean suspendEncoding;
        private final int options; // Record for later
        // private final byte[] alphabet; // Local copies to avoid extra method calls
        private final byte[] decodabet; // Local copies to avoid extra method calls
        
        /**
         * Constructs a {@link Base64.OutputStream} in ENCODE mode.
         * 
         * @param out
         *            the <tt>java.io.OutputStream</tt> to which data will be written.
         * @since 1.3
         */
        public OutputStream(java.io.OutputStream out)
        {
            this(out, ENCODE);
        } // end constructor
        
        /**
         * Constructs a {@link Base64.OutputStream} in either ENCODE or DECODE mode.
         * <p>
         * Valid options:
         * 
         * <pre>
         *   ENCODE or DECODE: Encode or Decode as data is read.
         *   DO_BREAK_LINES: don't break lines at 76 characters
         *     (only meaningful when encoding)&lt;/i&gt;
         * </pre>
         * <p>
         * Example: <code>new Base64.OutputStream( out, Base64.ENCODE )</code>
         * 
         * @param out
         *            the <tt>java.io.OutputStream</tt> to which data will be written.
         * @param options
         *            Specified options.
         * @see Base64#ENCODE
         * @see Base64#DECODE
         * @see Base64#DO_BREAK_LINES
         * @since 1.3
         */
        public OutputStream(java.io.OutputStream out, int options)
        {
            super(out);
            breakLines = (options & DO_BREAK_LINES) > 0;
            encode = (options & ENCODE) > 0;
            bufferLength = encode ? 3 : 4;
            buffer = new byte[bufferLength];
            position = 0;
            lineLength = 0;
            suspendEncoding = false;
            b4 = new byte[4];
            this.options = options;
            // alphabet = getAlphabet(options);
            decodabet = getDecodabet(options);
        } // end constructor
        
        /**
         * Flushes and closes (I think, in the superclass) the stream.
         * 
         * @since 1.3
         */
        @Override
        public void close() throws java.io.IOException
        {
            // 1. Ensure that pending characters are written
            flush();
            
            // 2. Actually close the stream
            // Base class both flushes and closes.
            super.close();
            
            buffer = null;
            out = null;
        } // end close
        
        /**
         * Flushes the stream (and the enclosing streams).
         * 
         * @throws java.io.IOException
         * @since 2.3
         */
        @Override
        public void flush() throws java.io.IOException
        {
            flushBase64();
            super.flush();
        }
        
        /**
         * Method added by PHIL. [Thanks, PHIL. -Rob] This pads the buffer without closing the
         * stream.
         * 
         * @throws java.io.IOException
         *             if there's an error.
         */
        public void flushBase64() throws java.io.IOException
        {
            if (position > 0)
                if (encode)
                {
                    out.write(encode3to4(b4, buffer, position, options));
                    position = 0;
                } // end if: encoding
                else
                    throw new java.io.IOException("Base64 input not properly padded.");
            
        } // end flush
        
        /**
         * Resumes encoding of the stream. May be helpful if you need to embed a piece of
         * base64-encoded data in a stream.
         * 
         * @since 1.5.1
         */
        public void resumeEncoding()
        {
            suspendEncoding = false;
        } // end resumeEncoding
        
        /**
         * Suspends encoding of the stream. May be helpful if you need to embed a piece of
         * base64-encoded data in a stream.
         * 
         * @throws java.io.IOException
         *             if there's an error flushing
         * @since 1.5.1
         */
        public void suspendEncoding() throws java.io.IOException
        {
            flushBase64();
            suspendEncoding = true;
        } // end suspendEncoding
        
        /**
         * Calls {@link #write(int)} repeatedly until <var>len</var> bytes are written.
         * 
         * @param theBytes
         *            array from which to read bytes
         * @param off
         *            offset for array
         * @param len
         *            max number of bytes to read into array
         * @since 1.3
         */
        @Override
        public void write(byte[] theBytes, int off, int len) throws java.io.IOException
        {
            // Encoding suspended?
            if (suspendEncoding)
            {
                super.out.write(theBytes, off, len);
                return;
            } // end if: supsended
            
            for (int i = 0; i < len; i++)
                write(theBytes[off + i]);
            
        } // end write
        
        /**
         * Writes the byte to the output stream after converting to/from Base64 notation. When
         * encoding, bytes are buffered three at a time before the output stream actually gets a
         * write() call. When decoding, bytes are buffered four at a time.
         * 
         * @param theByte
         *            the byte to write
         * @since 1.3
         */
        @Override
        public void write(int theByte) throws java.io.IOException
        {
            // Encoding suspended?
            if (suspendEncoding)
            {
                super.out.write(theByte);
                return;
            } // end if: supsended
            
            // Encode?
            if (encode)
            {
                buffer[position++] = (byte) theByte;
                if (position >= bufferLength)
                { // Enough to encode.
                
                    out.write(encode3to4(b4, buffer, bufferLength, options));
                    
                    lineLength += 4;
                    if (breakLines && lineLength >= MAX_LINE_LENGTH)
                    {
                        out.write(NEW_LINE);
                        lineLength = 0;
                    } // end if: end of line
                    
                    position = 0;
                } // end if: enough to output
            } // end if: encoding
            else // Meaningful Base64 character?
            if (decodabet[theByte & 0x7f] > WHITE_SPACE_ENC)
            {
                buffer[position++] = (byte) theByte;
                if (position >= bufferLength)
                { // Enough to output.
                
                    int len = Base64.decode4to3(buffer, 0, b4, 0, options);
                    out.write(b4, 0, len);
                    position = 0;
                } // end if: enough to output
            } // end if: meaningful base64 character
            else if (decodabet[theByte & 0x7f] != WHITE_SPACE_ENC)
                throw new java.io.IOException("Invalid character in Base64 data.");
        } // end write
        
    } // end inner class OutputStream
    
    /** No options specified. Value is zero. */
    public final static int NO_OPTIONS = 0;
    
    /** Specify encoding in first bit. Value is one. */
    public final static int ENCODE = 1;
    
    /** Specify decoding in first bit. Value is zero. */
    public final static int DECODE = 0;
    
    /** Specify that data should be gzip-compressed in second bit. Value is two. */
    public final static int GZIP = 2;
    
    /** Do break lines when encoding. Value is 8. */
    public final static int DO_BREAK_LINES = 8;
    
    /*          ******** P R I V A T E F I E L D S ******** */

    /**
     * Encode using Base64-like encoding that is URL- and Filename-safe as described in Section 4 of
     * RFC3548: <a
     * href="http://www.faqs.org/rfcs/rfc3548.html">http://www.faqs.org/rfcs/rfc3548.html</a>. It is
     * important to note that data encoded this way is <em>not</em> officially valid Base64, or at
     * the very least should not be called Base64 without also specifying that is was encoded using
     * the URL- and Filename-safe dialect.
     */
    public final static int URL_SAFE = 16;
    
    /**
     * Encode using the special "ordered" dialect of Base64 described here: <a
     * href="http://www.faqs.org/qa/rfcc-1940.html">http://www.faqs.org/qa/rfcc-1940.html</a>.
     */
    public final static int ORDERED = 32;
    
    /** Maximum line length (76) of Base64 output. */
    private final static int MAX_LINE_LENGTH = 76;
    
    /** The equals sign (=) as a byte. */
    private final static byte EQUALS_SIGN = (byte) '=';
    
    /** The new line character (\n) as a byte. */
    private final static byte NEW_LINE = (byte) '\n';
    /** Preferred encoding. */
    private final static String PREFERRED_ENCODING = "US-ASCII";
    
    /*          ******** S T A N D A R D B A S E 6 4 A L P H A B E T ******** */

    private final static byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding
    
    private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in encoding
    
    /*          ******** U R L S A F E B A S E 6 4 A L P H A B E T ******** */

    /** The 64 valid Base64 values. */
    /* Host platform me be something funny like EBCDIC, so we hardcode these values. */
    private final static byte[] _STANDARD_ALPHABET = { (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E',
            (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N',
            (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V', (byte) 'W',
            (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f',
            (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o',
            (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x',
            (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6',
            (byte) '7', (byte) '8', (byte) '9', (byte) '+', (byte) '/' };
    
    /**
     * Translates a Base64 value to either its 6-bit reconstruction value or a negative number
     * indicating some other meaning.
     **/
    private final static byte[] _STANDARD_DECODABET = { -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal
            // 0 - 8
            -5, -5, // Whitespace: Tab and Linefeed
            -9, -9, // Decimal 11 - 12
            -5, // Whitespace: Carriage Return
            -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
            -9, -9, -9, -9, -9, // Decimal 27 - 31
            -5, // Whitespace: Space
            -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42
            62, // Plus sign at decimal 43
            -9, -9, -9, // Decimal 44 - 46
            63, // Slash at decimal 47
            52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine
            -9, -9, -9, // Decimal 58 - 60
            -1, // Equals sign at decimal 61
            -9, -9, -9, // Decimal 62 - 64
            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N'
            14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z'
            -9, -9, -9, -9, -9, -9, // Decimal 91 - 96
            26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
            39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
            -9, -9, -9, -9 // Decimal 123 - 126
    /*
     * ,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 127 - 139
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 140 - 152
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 - 178
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 179 - 191
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 192 - 204
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 218 - 230
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255
     */
    };
    
    /*          ******** O R D E R E D B A S E 6 4 A L P H A B E T ******** */

    /**
     * Used in the URL- and Filename-safe dialect described in Section 4 of RFC3548: <a
     * href="http://www.faqs.org/rfcs/rfc3548.html">http://www.faqs.org/rfcs/rfc3548.html</a>.
     * Notice that the last two bytes become "hyphen" and "underscore" instead of "plus" and
     * "slash."
     */
    private final static byte[] _URL_SAFE_ALPHABET = { (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E',
            (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N',
            (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V', (byte) 'W',
            (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f',
            (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o',
            (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x',
            (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6',
            (byte) '7', (byte) '8', (byte) '9', (byte) '-', (byte) '_' };
    
    /**
     * Used in decoding URL- and Filename-safe dialects of Base64.
     */
    private final static byte[] _URL_SAFE_DECODABET = { -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal
            // 0 - 8
            -5, -5, // Whitespace: Tab and Linefeed
            -9, -9, // Decimal 11 - 12
            -5, // Whitespace: Carriage Return
            -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
            -9, -9, -9, -9, -9, // Decimal 27 - 31
            -5, // Whitespace: Space
            -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42
            -9, // Plus sign at decimal 43
            -9, // Decimal 44
            62, // Minus sign at decimal 45
            -9, // Decimal 46
            -9, // Slash at decimal 47
            52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine
            -9, -9, -9, // Decimal 58 - 60
            -1, // Equals sign at decimal 61
            -9, -9, -9, // Decimal 62 - 64
            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N'
            14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z'
            -9, -9, -9, -9, // Decimal 91 - 94
            63, // Underscore at decimal 95
            -9, // Decimal 96
            26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
            39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
            -9, -9, -9, -9 // Decimal 123 - 126
    /*
     * ,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 127 - 139
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 140 - 152
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 - 178
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 179 - 191
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 192 - 204
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 218 - 230
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255
     */
    };
    
    /*          ******** D E T E R M I N E W H I C H A L H A B E T ******** */

    /**
     * I don't get the point of this technique, but someone requested it, and it is described here:
     * <a href="http://www.faqs.org/qa/rfcc-1940.html">http://www.faqs.org/qa/rfcc-1940.html</a>.
     */
    private final static byte[] _ORDERED_ALPHABET = { (byte) '-', (byte) '0', (byte) '1', (byte) '2', (byte) '3',
            (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) 'A', (byte) 'B', (byte) 'C',
            (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L',
            (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U',
            (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) '_', (byte) 'a', (byte) 'b', (byte) 'c',
            (byte) 'd', (byte) 'e', (byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l',
            (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u',
            (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z' };
    
    /**
     * Used in decoding the "ordered" dialect of Base64.
     */
    private final static byte[] _ORDERED_DECODABET = { -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal
            // 0 - 8
            -5, -5, // Whitespace: Tab and Linefeed
            -9, -9, // Decimal 11 - 12
            -5, // Whitespace: Carriage Return
            -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
            -9, -9, -9, -9, -9, // Decimal 27 - 31
            -5, // Whitespace: Space
            -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42
            -9, // Plus sign at decimal 43
            -9, // Decimal 44
            0, // Minus sign at decimal 45
            -9, // Decimal 46
            -9, // Slash at decimal 47
            1, 2, 3, 4, 5, 6, 7, 8, 9, 10, // Numbers zero through nine
            -9, -9, -9, // Decimal 58 - 60
            -1, // Equals sign at decimal 61
            -9, -9, -9, // Decimal 62 - 64
            11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, // Letters 'A' through 'M'
            24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, // Letters 'N' through 'Z'
            -9, -9, -9, -9, // Decimal 91 - 94
            37, // Underscore at decimal 95
            -9, // Decimal 96
            38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, // Letters 'a' through 'm'
            51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, // Letters 'n' through 'z'
            -9, -9, -9, -9 // Decimal 123 - 126
    /*
     * ,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 127 - 139
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 140 - 152
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 - 178
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 179 - 191
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 192 - 204
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 218 - 230
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243
     * -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255
     */
    };
    
    /**
     * Low-level access to decoding ASCII characters in the form of a byte array. <strong>Ignores
     * GUNZIP option, if it's set.</strong> This is not generally a recommended method, although it
     * is used internally as part of the decoding process. Special case: if len = 0, an empty array
     * is returned. Still, if you need more speed and reduced memory footprint (and aren't
     * gzipping), consider this method.
     * 
     * @param source
     *            The Base64 encoded data
     * @return decoded data
     * @since 2.3.1
     */
    public static byte[] decode(byte[] source)
    {
        byte[] decoded = null;
        try
        {
            decoded = decode(source, 0, source.length, Base64.NO_OPTIONS);
        } catch (java.io.IOException ex)
        {
            assert false : "IOExceptions only come from GZipping, which is turned off: " + ex.getMessage();
        }
        return decoded;
    }
    
    /*          ******** E N C O D I N G M E T H O D S ******** */

    /**
     * Low-level access to decoding ASCII characters in the form of a byte array. <strong>Ignores
     * GUNZIP option, if it's set.</strong> This is not generally a recommended method, although it
     * is used internally as part of the decoding process. Special case: if len = 0, an empty array
     * is returned. Still, if you need more speed and reduced memory footprint (and aren't
     * gzipping), consider this method.
     * 
     * @param source
     *            The Base64 encoded data
     * @param off
     *            The offset of where to begin decoding
     * @param len
     *            The length of characters to decode
     * @param options
     *            Can specify options such as alphabet type to use
     * @return decoded data
     * @throws java.io.IOException
     *             If bogus characters exist in source data
     * @since 1.3
     */
    public static byte[] decode(byte[] source, int off, int len, int options) throws java.io.IOException
    {
        
        // Lots of error checking and exception throwing
        if (source == null)
            throw new NullPointerException("Cannot decode null source array.");
        if (off < 0 || off + len > source.length)
            throw new IllegalArgumentException(String.format(
                    "Source array with length %d cannot have offset of %d and process %d bytes.", source.length, off,
                    len));
        
        if (len == 0)
            return new byte[0];
        else if (len < 4)
            throw new IllegalArgumentException(
                    "Base64-encoded string must have at least four characters, but length specified was " + len);
        
        byte[] DECODABET = getDecodabet(options);
        
        int len34 = len * 3 / 4; // Estimate on array size
        byte[] outBuff = new byte[len34]; // Upper limit on size of output
        int outBuffPosn = 0; // Keep track of where we're writing
        
        byte[] b4 = new byte[4]; // Four byte buffer from source, eliminating white space
        int b4Posn = 0; // Keep track of four byte input buffer
        int i = 0; // Source array counter
        byte sbiCrop = 0; // Low seven bits (ASCII) of input
        byte sbiDecode = 0; // Special value from DECODABET
        
        for (i = off; i < off + len; i++)
        { // Loop through source
        
            sbiCrop = (byte) (source[i] & 0x7f); // Only the low seven bits
            sbiDecode = DECODABET[sbiCrop]; // Special value
            
            // White space, Equals sign, or legit Base64 character
            // Note the values such as -5 and -9 in the
            // DECODABETs at the top of the file.
            if (sbiDecode >= WHITE_SPACE_ENC)
            {
                if (sbiDecode >= EQUALS_SIGN_ENC)
                {
                    b4[b4Posn++] = sbiCrop; // Save non-whitespace
                    if (b4Posn > 3)
                    { // Time to decode?
                        outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, options);
                        b4Posn = 0;
                        
                        // If that was the equals sign, break out of 'for' loop
                        if (sbiCrop == EQUALS_SIGN)
                            break;
                    } // end if: quartet built
                } // end if: equals sign or better
            } // end if: white space, equals sign or better
            else
                // There's a bad input character in the Base64 stream.
                throw new java.io.IOException(String.format("Bad Base64 input character '%c' in array position %d",
                        source[i], i));
        } // each input character
        
        byte[] out = new byte[outBuffPosn];
        System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
        return out;
    } // end decode
    
    /**
     * Decodes data from Base64 notation, automatically detecting gzip-compressed data and
     * decompressing it.
     * 
     * @param s
     *            the string to decode
     * @return the decoded data
     * @throws java.io.IOException
     *             If there is a problem
     * @since 1.4
     */
    public static byte[] decode(String s) throws java.io.IOException
    {
        return decode(s, NO_OPTIONS);
    }
    
    /**
     * Decodes data from Base64 notation, automatically detecting gzip-compressed data and
     * decompressing it.
     * 
     * @param s
     *            the string to decode
     * @param options
     *            encode options such as URL_SAFE
     * @return the decoded data
     * @throws java.io.IOException
     *             if there is an error
     * @throws NullPointerException
     *             if <tt>s</tt> is null
     * @since 1.4
     */
    public static byte[] decode(String s, int options) throws java.io.IOException
    {
        
        if (s == null)
            throw new NullPointerException("Input string was null.");
        
        byte[] bytes;
        try
        {
            bytes = s.getBytes(PREFERRED_ENCODING);
        } // end try
        catch (java.io.UnsupportedEncodingException uee)
        {
            bytes = s.getBytes();
        } // end catch
        // </change>
        
        // Decode
        bytes = decode(bytes, 0, bytes.length, options);
        
        // Check to see if it's gzip-compressed
        // GZIP Magic Two-Byte Number: 0x8b1f (35615)
        if (bytes != null && bytes.length >= 4)
        {
            
            int head = bytes[0] & 0xff | bytes[1] << 8 & 0xff00;
            if (java.util.zip.GZIPInputStream.GZIP_MAGIC == head)
            {
                java.io.ByteArrayInputStream bais = null;
                java.util.zip.GZIPInputStream gzis = null;
                java.io.ByteArrayOutputStream baos = null;
                byte[] buffer = new byte[2048];
                int length = 0;
                
                try
                {
                    baos = new java.io.ByteArrayOutputStream();
                    bais = new java.io.ByteArrayInputStream(bytes);
                    gzis = new java.util.zip.GZIPInputStream(bais);
                    
                    while ((length = gzis.read(buffer)) >= 0)
                        baos.write(buffer, 0, length);
                    
                    // No error? Get new bytes.
                    bytes = baos.toByteArray();
                    
                } // end try
                catch (java.io.IOException e)
                {
                    // Just return originally-decoded bytes
                } // end catch
                finally
                {
                    try
                    {
                        baos.close();
                    } catch (Exception e)
                    {
                    }
                    try
                    {
                        gzis.close();
                    } catch (Exception e)
                    {
                    }
                    try
                    {
                        bais.close();
                    } catch (Exception e)
                    {
                    }
                } // end finally
                
            } // end if: gzipped
        } // end if: bytes.length >= 2
        
        return bytes;
    } // end decode
    
    /**
     * Reads <tt>infile</tt> and decodes it to <tt>outfile</tt>.
     * 
     * @param infile
     *            Input file
     * @param outfile
     *            Output file
     * @throws java.io.IOException
     *             if there is an error
     * @since 2.2
     */
    public static void decodeFileToFile(String infile, String outfile) throws java.io.IOException
    {
        
        byte[] decoded = Base64.decodeFromFile(infile);
        java.io.OutputStream out = null;
        try
        {
            out = new java.io.BufferedOutputStream(new java.io.FileOutputStream(outfile));
            out.write(decoded);
        } // end try
        catch (java.io.IOException e)
        {
            throw e; // Catch and release to execute finally{}
        } // end catch
        finally
        {
            try
            {
                out.close();
            } catch (Exception ex)
            {
            }
        } // end finally
    } // end decodeFileToFile
    
    /**
     * Convenience method for reading a base64-encoded file and decoding it.
     * 
     * <p>
     * As of v 2.3, if there is a error, the method will throw an java.io.IOException. <b>This is
     * new to v2.3!</b> In earlier versions, it just returned false, but in retrospect that's a
     * pretty poor way to handle it.
     * </p>
     * 
     * @param filename
     *            Filename for reading encoded data
     * @return decoded byte array
     * @throws java.io.IOException
     *             if there is an error
     * @since 2.1
     */
    public static byte[] decodeFromFile(String filename) throws java.io.IOException
    {
        
        byte[] decodedData = null;
        Base64.InputStream bis = null;
        try
        {
            // Set up some useful variables
            java.io.File file = new java.io.File(filename);
            byte[] buffer = null;
            int length = 0;
            int numBytes = 0;
            
            // Check for size of file
            if (file.length() > Integer.MAX_VALUE)
                throw new java.io.IOException("File is too big for this convenience method (" + file.length()
                        + " bytes).");
            buffer = new byte[(int) file.length()];
            
            // Open a stream
            bis = new Base64.InputStream(new java.io.BufferedInputStream(new java.io.FileInputStream(file)),
                    Base64.DECODE);
            
            // Read until done
            while ((numBytes = bis.read(buffer, length, 4096)) >= 0)
                length += numBytes;
            
            // Save in a variable to return
            decodedData = new byte[length];
            System.arraycopy(buffer, 0, decodedData, 0, length);
            
        } // end try
        catch (java.io.IOException e)
        {
            throw e; // Catch and release to execute finally{}
        } // end catch: java.io.IOException
        finally
        {
            try
            {
                bis.close();
            } catch (Exception e)
            {
            }
        } // end finally
        
        return decodedData;
    } // end decodeFromFile
    
    /**
     * Convenience method for decoding data to a file.
     * 
     * <p>
     * As of v 2.3, if there is a error, the method will throw an java.io.IOException. <b>This is
     * new to v2.3!</b> In earlier versions, it just returned false, but in retrospect that's a
     * pretty poor way to handle it.
     * </p>
     * 
     * @param dataToDecode
     *            Base64-encoded data as a string
     * @param filename
     *            Filename for saving decoded data
     * @throws java.io.IOException
     *             if there is an error
     * @since 2.1
     */
    public static void decodeToFile(String dataToDecode, String filename) throws java.io.IOException
    {
        
        Base64.OutputStream bos = null;
        try
        {
            bos = new Base64.OutputStream(new java.io.FileOutputStream(filename), Base64.DECODE);
            bos.write(dataToDecode.getBytes(PREFERRED_ENCODING));
        } // end try
        catch (java.io.IOException e)
        {
            throw e; // Catch and throw to execute finally{} block
        } // end catch: java.io.IOException
        finally
        {
            try
            {
                bos.close();
            } catch (Exception e)
            {
            }
        } // end finally
        
    } // end decodeToFile
    
    /**
     * Attempts to decode Base64 data and deserialize a Java Object within. Returns <tt>null</tt> if
     * there was an error.
     * 
     * @param encodedObject
     *            The Base64 data to decode
     * @return The decoded and deserialized object
     * @throws NullPointerException
     *             if encodedObject is null
     * @throws java.io.IOException
     *             if there is a general error
     * @throws ClassNotFoundException
     *             if the decoded object is of a class that cannot be found by the JVM
     * @since 1.5
     */
    public static Object decodeToObject(String encodedObject) throws java.io.IOException,
            java.lang.ClassNotFoundException
    {
        
        // Decode and gunzip if necessary
        byte[] objBytes = decode(encodedObject);
        
        java.io.ByteArrayInputStream bais = null;
        java.io.ObjectInputStream ois = null;
        Object obj = null;
        
        try
        {
            bais = new java.io.ByteArrayInputStream(objBytes);
            ois = new java.io.ObjectInputStream(bais);
            
            obj = ois.readObject();
        } // end try
        catch (java.io.IOException e)
        {
            throw e; // Catch and throw in order to execute finally{}
        } // end catch
        catch (java.lang.ClassNotFoundException e)
        {
            throw e; // Catch and throw in order to execute finally{}
        } // end catch
        finally
        {
            try
            {
                bais.close();
            } catch (Exception e)
            {
            }
            try
            {
                ois.close();
            } catch (Exception e)
            {
            }
        } // end finally
        
        return obj;
    } // end decodeObject
    
    /**
     * Performs Base64 encoding on the <code>raw</code> ByteBuffer, writing it to the
     * <code>encoded</code> ByteBuffer. This is an experimental feature. Currently it does not pass
     * along any options (such as {@link #DO_BREAK_LINES} or {@link #GZIP}.
     * 
     * @param raw
     *            input buffer
     * @param encoded
     *            output buffer
     * @since 2.3
     */
    public static void encode(java.nio.ByteBuffer raw, java.nio.ByteBuffer encoded)
    {
        byte[] raw3 = new byte[3];
        byte[] enc4 = new byte[4];
        
        while (raw.hasRemaining())
        {
            int rem = Math.min(3, raw.remaining());
            raw.get(raw3, 0, rem);
            Base64.encode3to4(enc4, raw3, rem, Base64.NO_OPTIONS);
            encoded.put(enc4);
        } // end input remaining
    }
    
    /**
     * Performs Base64 encoding on the <code>raw</code> ByteBuffer, writing it to the
     * <code>encoded</code> CharBuffer. This is an experimental feature. Currently it does not pass
     * along any options (such as {@link #DO_BREAK_LINES} or {@link #GZIP}.
     * 
     * @param raw
     *            input buffer
     * @param encoded
     *            output buffer
     * @since 2.3
     */
    public static void encode(java.nio.ByteBuffer raw, java.nio.CharBuffer encoded)
    {
        byte[] raw3 = new byte[3];
        byte[] enc4 = new byte[4];
        
        while (raw.hasRemaining())
        {
            int rem = Math.min(3, raw.remaining());
            raw.get(raw3, 0, rem);
            Base64.encode3to4(enc4, raw3, rem, Base64.NO_OPTIONS);
            for (int i = 0; i < 4; i++)
                encoded.put((char) (enc4[i] & 0xFF));
        } // end input remaining
    }
    
    /**
     * Encodes a byte array into Base64 notation. Does not GZip-compress data.
     * 
     * @param source
     *            The data to convert
     * @return The data in Base64-encoded form
     * @throws NullPointerException
     *             if source array is null
     * @since 1.4
     */
    public static String encodeBytes(byte[] source)
    {
        // Since we're not going to have the GZIP encoding turned on,
        // we're not going to have an java.io.IOException thrown, so
        // we should not force the user to have to catch it.
        String encoded = null;
        try
        {
            encoded = encodeBytes(source, 0, source.length, NO_OPTIONS);
        } catch (java.io.IOException ex)
        {
            assert false : ex.getMessage();
        } // end catch
        assert encoded != null;
        return encoded;
    } // end encodeBytes
    
    /**
     * Encodes a byte array into Base64 notation.
     * <p>
     * Example options:
     * 
     * <pre>
     *   GZIP: gzip-compresses object before encoding it.
     *   DO_BREAK_LINES: break lines at 76 characters
     *     &lt;i&gt;Note: Technically, this makes your encoding non-compliant.&lt;/i&gt;
     * </pre>
     * <p>
     * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
     * <p>
     * Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
     * 
     * 
     * <p>
     * As of v 2.3, if there is an error with the GZIP stream, the method will throw an
     * java.io.IOException. <b>This is new to v2.3!</b> In earlier versions, it just returned a null
     * value, but in retrospect that's a pretty poor way to handle it.
     * </p>
     * 
     * 
     * @param source
     *            The data to convert
     * @param options
     *            Specified options
     * @return The Base64-encoded data as a String
     * @see Base64#GZIP
     * @see Base64#DO_BREAK_LINES
     * @throws java.io.IOException
     *             if there is an error
     * @throws NullPointerException
     *             if source array is null
     * @since 2.0
     */
    public static String encodeBytes(byte[] source, int options) throws java.io.IOException
    {
        return encodeBytes(source, 0, source.length, options);
    } // end encodeBytes
    
    /**
     * Encodes a byte array into Base64 notation. Does not GZip-compress data.
     * 
     * <p>
     * As of v 2.3, if there is an error, the method will throw an java.io.IOException. <b>This is
     * new to v2.3!</b> In earlier versions, it just returned a null value, but in retrospect that's
     * a pretty poor way to handle it.
     * </p>
     * 
     * 
     * @param source
     *            The data to convert
     * @param off
     *            Offset in array where conversion should begin
     * @param len
     *            Length of data to convert
     * @return The Base64-encoded data as a String
     * @throws NullPointerException
     *             if source array is null
     * @throws IllegalArgumentException
     *             if source array, offset, or length are invalid
     * @since 1.4
     */
    public static String encodeBytes(byte[] source, int off, int len)
    {
        // Since we're not going to have the GZIP encoding turned on,
        // we're not going to have an java.io.IOException thrown, so
        // we should not force the user to have to catch it.
        String encoded = null;
        try
        {
            encoded = encodeBytes(source, off, len, NO_OPTIONS);
        } catch (java.io.IOException ex)
        {
            assert false : ex.getMessage();
        } // end catch
        assert encoded != null;
        return encoded;
    } // end encodeBytes
    
    /**
     * Encodes a byte array into Base64 notation.
     * <p>
     * Example options:
     * 
     * <pre>
     *   GZIP: gzip-compresses object before encoding it.
     *   DO_BREAK_LINES: break lines at 76 characters
     *     &lt;i&gt;Note: Technically, this makes your encoding non-compliant.&lt;/i&gt;
     * </pre>
     * <p>
     * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
     * <p>
     * Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
     * 
     * 
     * <p>
     * As of v 2.3, if there is an error with the GZIP stream, the method will throw an
     * java.io.IOException. <b>This is new to v2.3!</b> In earlier versions, it just returned a null
     * value, but in retrospect that's a pretty poor way to handle it.
     * </p>
     * 
     * 
     * @param source
     *            The data to convert
     * @param off
     *            Offset in array where conversion should begin
     * @param len
     *            Length of data to convert
     * @param options
     *            Specified options
     * @return The Base64-encoded data as a String
     * @see Base64#GZIP
     * @see Base64#DO_BREAK_LINES
     * @throws java.io.IOException
     *             if there is an error
     * @throws NullPointerException
     *             if source array is null
     * @throws IllegalArgumentException
     *             if source array, offset, or length are invalid
     * @since 2.0
     */
    public static String encodeBytes(byte[] source, int off, int len, int options) throws java.io.IOException
    {
        byte[] encoded = encodeBytesToBytes(source, off, len, options);
        
        // Return value according to relevant encoding.
        try
        {
            return new String(encoded, PREFERRED_ENCODING);
        } // end try
        catch (java.io.UnsupportedEncodingException uue)
        {
            return new String(encoded);
        } // end catch
        
    } // end encodeBytes
    
    /**
     * Similar to {@link #encodeBytes(byte[])} but returns a byte array instead of instantiating a
     * String. This is more efficient if you're working with I/O streams and have large data sets to
     * encode.
     * 
     * 
     * @param source
     *            The data to convert
     * @return The Base64-encoded data as a byte[] (of ASCII characters)
     * @throws NullPointerException
     *             if source array is null
     * @since 2.3.1
     */
    public static byte[] encodeBytesToBytes(byte[] source)
    {
        byte[] encoded = null;
        try
        {
            encoded = encodeBytesToBytes(source, 0, source.length, Base64.NO_OPTIONS);
        } catch (java.io.IOException ex)
        {
            assert false : "IOExceptions only come from GZipping, which is turned off: " + ex.getMessage();
        }
        return encoded;
    }
    
    /**
     * Similar to {@link #encodeBytes(byte[], int, int, int)} but returns a byte array instead of
     * instantiating a String. This is more efficient if you're working with I/O streams and have
     * large data sets to encode.
     * 
     * 
     * @param source
     *            The data to convert
     * @param off
     *            Offset in array where conversion should begin
     * @param len
     *            Length of data to convert
     * @param options
     *            Specified options
     * @return The Base64-encoded data as a String
     * @see Base64#GZIP
     * @see Base64#DO_BREAK_LINES
     * @throws java.io.IOException
     *             if there is an error
     * @throws NullPointerException
     *             if source array is null
     * @throws IllegalArgumentException
     *             if source array, offset, or length are invalid
     * @since 2.3.1
     */
    public static byte[] encodeBytesToBytes(byte[] source, int off, int len, int options) throws java.io.IOException
    {
        
        if (source == null)
            throw new NullPointerException("Cannot serialize a null array.");
        
        if (off < 0)
            throw new IllegalArgumentException("Cannot have negative offset: " + off);
        
        if (len < 0)
            throw new IllegalArgumentException("Cannot have length offset: " + len);
        
        if (off + len > source.length)
            throw new IllegalArgumentException(String.format(
                    "Cannot have offset of %d and length of %d with array of length %d", off, len, source.length));
        
        // Compress?
        if ((options & GZIP) > 0)
        {
            java.io.ByteArrayOutputStream baos = null;
            java.util.zip.GZIPOutputStream gzos = null;
            Base64.OutputStream b64os = null;
            
            try
            {
                // GZip -> Base64 -> ByteArray
                baos = new java.io.ByteArrayOutputStream();
                b64os = new Base64.OutputStream(baos, ENCODE | options);
                gzos = new java.util.zip.GZIPOutputStream(b64os);
                
                gzos.write(source, off, len);
                gzos.close();
            } // end try
            catch (java.io.IOException e)
            {
                // Catch it and then throw it immediately so that
                // the finally{} block is called for cleanup.
                throw e;
            } // end catch
            finally
            {
                try
                {
                    gzos.close();
                } catch (Exception e)
                {
                }
                try
                {
                    b64os.close();
                } catch (Exception e)
                {
                }
                try
                {
                    baos.close();
                } catch (Exception e)
                {
                }
            } // end finally
            
            return baos.toByteArray();
        } // end if: compress
        
        // Else, don't compress. Better not to use streams at all then.
        else
        {
            boolean breakLines = (options & DO_BREAK_LINES) > 0;
            
            // int len43 = len * 4 / 3;
            // byte[] outBuff = new byte[ ( len43 ) // Main 4:3
            // + ( (len % 3) > 0 ? 4 : 0 ) // Account for padding
            // + (breakLines ? ( len43 / MAX_LINE_LENGTH ) : 0) ]; // New lines
            // Try to determine more precisely how big the array needs to be.
            // If we get it right, we don't have to do an array copy, and
            // we save a bunch of memory.
            int encLen = len / 3 * 4 + (len % 3 > 0 ? 4 : 0); // Bytes needed for actual encoding
            if (breakLines)
                encLen += encLen / MAX_LINE_LENGTH; // Plus extra newline characters
            byte[] outBuff = new byte[encLen];
            
            int d = 0;
            int e = 0;
            int len2 = len - 2;
            int lineLength = 0;
            for (; d < len2; d += 3, e += 4)
            {
                encode3to4(source, d + off, 3, outBuff, e, options);
                
                lineLength += 4;
                if (breakLines && lineLength >= MAX_LINE_LENGTH)
                {
                    outBuff[e + 4] = NEW_LINE;
                    e++;
                    lineLength = 0;
                } // end if: end of line
            } // en dfor: each piece of array
            
            if (d < len)
            {
                encode3to4(source, d + off, len - d, outBuff, e, options);
                e += 4;
            } // end if: some padding needed
            
            // Only resize array if we didn't guess it right.
            if (e < outBuff.length - 1)
            {
                byte[] finalOut = new byte[e];
                System.arraycopy(outBuff, 0, finalOut, 0, e);
                // System.err.println("Having to resize array from " + outBuff.length + " to " + e
                // );
                return finalOut;
            } else
                // System.err.println("No need to resize array.");
                return outBuff;
            
        } // end else: don't compress
        
    } // end encodeBytesToBytes
    
    /**
     * Reads <tt>infile</tt> and encodes it to <tt>outfile</tt>.
     * 
     * @param infile
     *            Input file
     * @param outfile
     *            Output file
     * @throws java.io.IOException
     *             if there is an error
     * @since 2.2
     */
    public static void encodeFileToFile(String infile, String outfile) throws java.io.IOException
    {
        
        String encoded = Base64.encodeFromFile(infile);
        java.io.OutputStream out = null;
        try
        {
            out = new java.io.BufferedOutputStream(new java.io.FileOutputStream(outfile));
            out.write(encoded.getBytes("US-ASCII")); // Strict, 7-bit output.
        } // end try
        catch (java.io.IOException e)
        {
            throw e; // Catch and release to execute finally{}
        } // end catch
        finally
        {
            try
            {
                out.close();
            } catch (Exception ex)
            {
            }
        } // end finally
    } // end encodeFileToFile
    
    /**
     * Convenience method for reading a binary file and base64-encoding it.
     * 
     * <p>
     * As of v 2.3, if there is a error, the method will throw an java.io.IOException. <b>This is
     * new to v2.3!</b> In earlier versions, it just returned false, but in retrospect that's a
     * pretty poor way to handle it.
     * </p>
     * 
     * @param filename
     *            Filename for reading binary data
     * @return base64-encoded string
     * @throws java.io.IOException
     *             if there is an error
     * @since 2.1
     */
    public static String encodeFromFile(String filename) throws java.io.IOException
    {
        
        String encodedData = null;
        Base64.InputStream bis = null;
        try
        {
            // Set up some useful variables
            java.io.File file = new java.io.File(filename);
            byte[] buffer = new byte[Math.max((int) (file.length() * 1.4), 40)]; // Need max() for
            // math on small
            // files (v2.2.1)
            int length = 0;
            int numBytes = 0;
            
            // Open a stream
            bis = new Base64.InputStream(new java.io.BufferedInputStream(new java.io.FileInputStream(file)),
                    Base64.ENCODE);
            
            // Read until done
            while ((numBytes = bis.read(buffer, length, 4096)) >= 0)
                length += numBytes;
            
            // Save in a variable to return
            encodedData = new String(buffer, 0, length, Base64.PREFERRED_ENCODING);
            
        } // end try
        catch (java.io.IOException e)
        {
            throw e; // Catch and release to execute finally{}
        } // end catch: java.io.IOException
        finally
        {
            try
            {
                bis.close();
            } catch (Exception e)
            {
            }
        } // end finally
        
        return encodedData;
    } // end encodeFromFile
    
    /**
     * Serializes an object and returns the Base64-encoded version of that serialized object.
     * 
     * <p>
     * As of v 2.3, if the object cannot be serialized or there is another error, the method will
     * throw an java.io.IOException. <b>This is new to v2.3!</b> In earlier versions, it just
     * returned a null value, but in retrospect that's a pretty poor way to handle it.
     * </p>
     * 
     * The object is not GZip-compressed before being encoded.
     * 
     * @param serializableObject
     *            The object to encode
     * @return The Base64-encoded object
     * @throws java.io.IOException
     *             if there is an error
     * @throws NullPointerException
     *             if serializedObject is null
     * @since 1.4
     */
    public static String encodeObject(java.io.Serializable serializableObject) throws java.io.IOException
    {
        return encodeObject(serializableObject, NO_OPTIONS);
    } // end encodeObject
    
    /**
     * Serializes an object and returns the Base64-encoded version of that serialized object.
     * 
     * <p>
     * As of v 2.3, if the object cannot be serialized or there is another error, the method will
     * throw an java.io.IOException. <b>This is new to v2.3!</b> In earlier versions, it just
     * returned a null value, but in retrospect that's a pretty poor way to handle it.
     * </p>
     * 
     * The object is not GZip-compressed before being encoded.
     * <p>
     * Example options:
     * 
     * <pre>
     *   GZIP: gzip-compresses object before encoding it.
     *   DO_BREAK_LINES: break lines at 76 characters
     * </pre>
     * <p>
     * Example: <code>encodeObject( myObj, Base64.GZIP )</code> or
     * <p>
     * Example: <code>encodeObject( myObj, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
     * 
     * @param serializableObject
     *            The object to encode
     * @param options
     *            Specified options
     * @return The Base64-encoded object
     * @see Base64#GZIP
     * @see Base64#DO_BREAK_LINES
     * @throws java.io.IOException
     *             if there is an error
     * @since 2.0
     */
    public static String encodeObject(java.io.Serializable serializableObject, int options) throws java.io.IOException
    {
        
        if (serializableObject == null)
            throw new NullPointerException("Cannot serialize a null object.");
        
        // Streams
        java.io.ByteArrayOutputStream baos = null;
        java.io.OutputStream b64os = null;
        java.io.ObjectOutputStream oos = null;
        
        try
        {
            // ObjectOutputStream -> (GZIP) -> Base64 -> ByteArrayOutputStream
            // Note that the optional GZIPping is handled by Base64.OutputStream.
            baos = new java.io.ByteArrayOutputStream();
            b64os = new Base64.OutputStream(baos, ENCODE | options);
            oos = new java.io.ObjectOutputStream(b64os);
            oos.writeObject(serializableObject);
        } // end try
        catch (java.io.IOException e)
        {
            // Catch it and then throw it immediately so that
            // the finally{} block is called for cleanup.
            throw e;
        } // end catch
        finally
        {
            try
            {
                oos.close();
            } catch (Exception e)
            {
            }
            try
            {
                b64os.close();
            } catch (Exception e)
            {
            }
            try
            {
                baos.close();
            } catch (Exception e)
            {
            }
        } // end finally
        
        // Return value according to relevant encoding.
        try
        {
            return new String(baos.toByteArray(), PREFERRED_ENCODING);
        } // end try
        catch (java.io.UnsupportedEncodingException uue)
        {
            // Fall back to some Java default
            return new String(baos.toByteArray());
        } // end catch
        
    } // end encode
    
    /**
     * Convenience method for encoding data to a file.
     * 
     * <p>
     * As of v 2.3, if there is a error, the method will throw an java.io.IOException. <b>This is
     * new to v2.3!</b> In earlier versions, it just returned false, but in retrospect that's a
     * pretty poor way to handle it.
     * </p>
     * 
     * @param dataToEncode
     *            byte array of data to encode in base64 form
     * @param filename
     *            Filename for saving encoded data
     * @throws java.io.IOException
     *             if there is an error
     * @throws NullPointerException
     *             if dataToEncode is null
     * @since 2.1
     */
    public static void encodeToFile(byte[] dataToEncode, String filename) throws java.io.IOException
    {
        
        if (dataToEncode == null)
            throw new NullPointerException("Data to encode was null.");
        
        Base64.OutputStream bos = null;
        try
        {
            bos = new Base64.OutputStream(new java.io.FileOutputStream(filename), Base64.ENCODE);
            bos.write(dataToEncode);
        } // end try
        catch (java.io.IOException e)
        {
            throw e; // Catch and throw to execute finally{} block
        } // end catch: java.io.IOException
        finally
        {
            try
            {
                bos.close();
            } catch (Exception e)
            {
            }
        } // end finally
        
    } // end encodeToFile
    
    /**
     * Decodes four bytes from array <var>source</var> and writes the resulting bytes (up to three
     * of them) to <var>destination</var>. The source and destination arrays can be manipulated
     * anywhere along their length by specifying <var>srcOffset</var> and <var>destOffset</var>.
     * This method does not check to make sure your arrays are large enough to accomodate
     * <var>srcOffset</var> + 4 for the <var>source</var> array or <var>destOffset</var> + 3 for the
     * <var>destination</var> array. This method returns the actual number of bytes that were
     * converted from the Base64 encoding.
     * <p>
     * This is the lowest level of the decoding methods with all possible parameters.
     * </p>
     * 
     * 
     * @param source
     *            the array to convert
     * @param srcOffset
     *            the index where conversion begins
     * @param destination
     *            the array to hold the conversion
     * @param destOffset
     *            the index where output will be put
     * @param options
     *            alphabet type is pulled from this (standard, url-safe, ordered)
     * @return the number of decoded bytes converted
     * @throws NullPointerException
     *             if source or destination arrays are null
     * @throws IllegalArgumentException
     *             if srcOffset or destOffset are invalid or there is not enough room in the array.
     * @since 1.3
     */
    private static int decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset, int options)
    {
        
        // Lots of error checking and exception throwing
        if (source == null)
            throw new NullPointerException("Source array was null.");
        if (destination == null)
            throw new NullPointerException("Destination array was null.");
        if (srcOffset < 0 || srcOffset + 3 >= source.length)
            throw new IllegalArgumentException(String.format(
                    "Source array with length %d cannot have offset of %d and still process four bytes.",
                    source.length, srcOffset));
        if (destOffset < 0 || destOffset + 2 >= destination.length)
            throw new IllegalArgumentException(String.format(
                    "Destination array with length %d cannot have offset of %d and still store three bytes.",
                    destination.length, destOffset));
        
        byte[] DECODABET = getDecodabet(options);
        
        // Example: Dk==
        if (source[srcOffset + 2] == EQUALS_SIGN)
        {
            // Two ways to do the same thing. Don't know which way I like best.
            // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
            // | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 );
            int outBuff = (DECODABET[source[srcOffset]] & 0xFF) << 18 | (DECODABET[source[srcOffset + 1]] & 0xFF) << 12;
            
            destination[destOffset] = (byte) (outBuff >>> 16);
            return 1;
        }

        // Example: DkL=
        else if (source[srcOffset + 3] == EQUALS_SIGN)
        {
            // Two ways to do the same thing. Don't know which way I like best.
            // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
            // | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
            // | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 );
            int outBuff = (DECODABET[source[srcOffset]] & 0xFF) << 18 | (DECODABET[source[srcOffset + 1]] & 0xFF) << 12
                    | (DECODABET[source[srcOffset + 2]] & 0xFF) << 6;
            
            destination[destOffset] = (byte) (outBuff >>> 16);
            destination[destOffset + 1] = (byte) (outBuff >>> 8);
            return 2;
        }

        // Example: DkLE
        else
        {
            // Two ways to do the same thing. Don't know which way I like best.
            // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
            // | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
            // | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 )
            // | ( ( DECODABET[ source[ srcOffset + 3 ] ] << 24 ) >>> 24 );
            int outBuff = (DECODABET[source[srcOffset]] & 0xFF) << 18 | (DECODABET[source[srcOffset + 1]] & 0xFF) << 12
                    | (DECODABET[source[srcOffset + 2]] & 0xFF) << 6 | DECODABET[source[srcOffset + 3]] & 0xFF;
            
            destination[destOffset] = (byte) (outBuff >> 16);
            destination[destOffset + 1] = (byte) (outBuff >> 8);
            destination[destOffset + 2] = (byte) outBuff;
            
            return 3;
        }
    } // end decodeToBytes
    
    /**
     * Encodes up to the first three bytes of array <var>threeBytes</var> and returns a four-byte
     * array in Base64 notation. The actual number of significant bytes in your array is given by
     * <var>numSigBytes</var>. The array <var>threeBytes</var> needs only be as big as
     * <var>numSigBytes</var>. Code can reuse a byte array by passing a four-byte array as
     * <var>b4</var>.
     * 
     * @param b4
     *            A reusable byte array to reduce array instantiation
     * @param threeBytes
     *            the array to convert
     * @param numSigBytes
     *            the number of significant bytes in your array
     * @return four byte array in Base64 notation.
     * @since 1.5.1
     */
    private static byte[] encode3to4(byte[] b4, byte[] threeBytes, int numSigBytes, int options)
    {
        encode3to4(threeBytes, 0, numSigBytes, b4, 0, options);
        return b4;
    } // end encode3to4
    
    /**
     * <p>
     * Encodes up to three bytes of the array <var>source</var> and writes the resulting four Base64
     * bytes to <var>destination</var>. The source and destination arrays can be manipulated
     * anywhere along their length by specifying <var>srcOffset</var> and <var>destOffset</var>.
     * This method does not check to make sure your arrays are large enough to accomodate
     * <var>srcOffset</var> + 3 for the <var>source</var> array or <var>destOffset</var> + 4 for the
     * <var>destination</var> array. The actual number of significant bytes in your array is given
     * by <var>numSigBytes</var>.
     * </p>
     * <p>
     * This is the lowest level of the encoding methods with all possible parameters.
     * </p>
     * 
     * @param source
     *            the array to convert
     * @param srcOffset
     *            the index where conversion begins
     * @param numSigBytes
     *            the number of significant bytes in your array
     * @param destination
     *            the array to hold the conversion
     * @param destOffset
     *            the index where output will be put
     * @return the <var>destination</var> array
     * @since 1.3
     */
    private static byte[] encode3to4(byte[] source, int srcOffset, int numSigBytes, byte[] destination, int destOffset,
            int options)
    {
        
        byte[] ALPHABET = getAlphabet(options);
        
        // 1 2 3
        // 01234567890123456789012345678901 Bit position
        // --------000000001111111122222222 Array position from threeBytes
        // --------| || || || | Six bit groups to index ALPHABET
        // >>18 >>12 >> 6 >> 0 Right shift necessary
        // 0x3f 0x3f 0x3f Additional AND
        
        // Create buffer with zero-padding if there are only one or two
        // significant bytes passed in the array.
        // We have to shift left 24 in order to flush out the 1's that appear
        // when Java treats a value as negative that is cast from a byte to an int.
        int inBuff = (numSigBytes > 0 ? source[srcOffset] << 24 >>> 8 : 0)
                | (numSigBytes > 1 ? source[srcOffset + 1] << 24 >>> 16 : 0)
                | (numSigBytes > 2 ? source[srcOffset + 2] << 24 >>> 24 : 0);
        
        switch (numSigBytes)
        {
        case 3:
            destination[destOffset] = ALPHABET[(inBuff >>> 18)];
            destination[destOffset + 1] = ALPHABET[inBuff >>> 12 & 0x3f];
            destination[destOffset + 2] = ALPHABET[inBuff >>> 6 & 0x3f];
            destination[destOffset + 3] = ALPHABET[inBuff & 0x3f];
            return destination;
            
        case 2:
            destination[destOffset] = ALPHABET[(inBuff >>> 18)];
            destination[destOffset + 1] = ALPHABET[inBuff >>> 12 & 0x3f];
            destination[destOffset + 2] = ALPHABET[inBuff >>> 6 & 0x3f];
            destination[destOffset + 3] = EQUALS_SIGN;
            return destination;
            
        case 1:
            destination[destOffset] = ALPHABET[(inBuff >>> 18)];
            destination[destOffset + 1] = ALPHABET[inBuff >>> 12 & 0x3f];
            destination[destOffset + 2] = EQUALS_SIGN;
            destination[destOffset + 3] = EQUALS_SIGN;
            return destination;
            
        default:
            return destination;
        } // end switch
    } // end encode3to4
    
    /**
     * Returns one of the _SOMETHING_ALPHABET byte arrays depending on the options specified. It's
     * possible, though silly, to specify ORDERED <b>and</b> URLSAFE in which case one of them will
     * be picked, though there is no guarantee as to which one will be picked.
     */
    private final static byte[] getAlphabet(int options)
    {
        if ((options & URL_SAFE) == URL_SAFE)
            return _URL_SAFE_ALPHABET;
        else if ((options & ORDERED) == ORDERED)
            return _ORDERED_ALPHABET;
        else
            return _STANDARD_ALPHABET;
    } // end getAlphabet
    
    /**
     * Returns one of the _SOMETHING_DECODABET byte arrays depending on the options specified. It's
     * possible, though silly, to specify ORDERED and URL_SAFE in which case one of them will be
     * picked, though there is no guarantee as to which one will be picked.
     */
    private final static byte[] getDecodabet(int options)
    {
        if ((options & URL_SAFE) == URL_SAFE)
            return _URL_SAFE_DECODABET;
        else if ((options & ORDERED) == ORDERED)
            return _ORDERED_DECODABET;
        else
            return _STANDARD_DECODABET;
    } // end getAlphabet
    
    /** Defeats instantiation. */
    private Base64()
    {
    }
    
} // end class Base64